Plural flourescent lamp starting circuit using an unignited lamp as ballast and a flux leakage transformer as to obtain suitable control voltages

ABSTRACT

A starting system for gaseous discharge devices, in which a transformer is used, comprising a magnetic core having two sections, a plurality of primary windings wound about one section, and a plurality of secondary windings, one portion wound about the one section commonly with the primary windings, and another portion wound about the other section, with suitable connections of the secondary windings to the discharge devices. The split secondary windings on different sections of the core, acts as a transformer and ballast choke.

United States Patent inventor Shungo Furui 1394 Namanugi-cho, Surum Ku,Yokohama, Japan Appl. No. 758,461 Filed Sept. 9, 1968 Patented June 1,1971 Priority Sept. 23, 1967 Japan 42/061 141 PLURAL FLOURESCENT LAMP-STARTING CIRCUIT USING AN UNIGNITED LAMP AS BALLAST AND A FLUX LEAKAGETRANSFORMER AS TO OBTAIN SUITABLE CONTROL VOLTAGES 3 Claims, 2 DrawingFigs.

US. Cl 315/96,

315/99, 315/254, 315/257, 315/278, 336/170 Int. Cl 1105b 41/18, H01227/28 Field ofSear-eh 315/94, 95, 96,98,100,105,l07,185,254,157,156,l78,323; 336/170 [56] References Cited UNITED STATES PATENTS 2,940,0086/1960 Strecker 315/98X 2,947,909 8/1960 Berger... 315/100 3,315,1234/1967 Furui 315/100 FOREIGN PATENTS 616,049 1/1949 Great Britain 315/94Primary Examiner-John Kominski Assistant Examiner-E. R. LaRocheAttorney-Moonray Kojima ABSTRACT: A starting system for gaseousdischarge devices, in which a transformer is used, comprising a magneticcore having two sections, a plurality of primary windings wound aboutone section, and a plurality of secondary windings, one portion woundabout the one section commonly with the primary windings, and anotherportion wound about the othersection, with suitable connections of thesecondary windings to the discharge devices. The split secondarywindings on different sections of the core, acts as a transformer andballast choke.

PATENIEnJlm n92: 3,'5a2',709

Fl 6 2 INVENTOR SHUNGO FURUI ATTORNEY PLURAL FLOURESCENT LAMP STARTINGCIRCUIT USING AN UNIGNITED LAMP AS BALLAST AND A FLUX LEAKAGETRANSFORMER AS TO OBTAIN SUITABLE CONTROL VOLTAGES DISCLOSURE Thisinvention relates to a system for operating gaseous discharge devices.

An object of the invention is to provide a starting and operating systemfor gaseous discharge devices, such as fluorescent lamps, which does notrequire the heavy duty inductive or impedance-type ballasts used in theprior art systems, and which system will improve current regulation.

The foregoing and other objects are attained in an illustrativeembodiment of this invention which employs a transformer comprising amagnetic core having a first and a second section, a plurality ofprimary windings wound on the first section, and a plurality ofsecondary winding having a first portion wound about the first sectioncommonly with the primary windings, and a second portion wound about thesecond section of the magnetic core. The secondary windings areconnected to the filaments of one or more gaseous discharge devices.

The secondary windings wound about the second section of the magneticcore have a sufiicient amount of flux leakage to cause the secondarywindings to act as both transformer and ballast choke. Additionalballasts have been found to not be required with use of the transformerof this invention, in starting circuits for gaseous discharge device.Advantageously, economy of power, efficiency, greater current stability,and reduction in physical size result from use of this invention.

These and other objects, features andadvantageous results of thisinvention will become more apparent from a considera tion of thefollowing detailed description taken in connection with the followingdrawing, in which:

FIG. 1, depicts an illustrative embodiment of this invention inconnection with a 'pair of preheated-type (FL) fluorescent lamp, and

FIG. 2, depicts another illustrative embodiment of this invention inconnection with a pair of rapid start-type (FLR) fluorescent lamps.

Turning now to the drawing, in FIG. I, there is depicted a transformercomprising a magnetic core 1, primary windings 2A and 2B wound about onesection of core l and secondary windings comprising portions 3A and 3Cwound (although shown only symbolically) commonly about the same sectionof core 1 with the primary windings 2A and 2B. A fluxleakage path isadditionally provided by magnetic conductor 1A.

The primary windings 2A and 2B are connected via switch S to generatoror power source G. Connected to terminal 17 of the secondary windings iscapacitor 4, which is connected in shunt to static discharge resistor12, filter inductor l8, and filament 6B of preheated-type (FL)fluorescent lamp 6. The other terminal l6 of the secondary windings isconnected to primary winding-2B as depicted. Terminal 15 is connected toimpedance 7 and filament 5A of preheated-type (FL) fluorescent lamp 5.

Lamps 5 and6 are-connected in series circuit toeach other as depicted,with impedance 7 connected in parallel circuit across lamp 5. Alsoconnected in parallel across lamp 5 is a shunt combination of glowstarter switch 8 and noise suppressing capacitor 10. A similarcombination of glow starter switch 9 and noise suppressingcapacitor ii,is connected in shunt circuitacross lamp 6.

In operation, when switch S is closed, current is applied throughprimary windings 2A and 28 to cause'higher voltage outof secondarywinding 3A, 3B, 3C and 3D, which higher voltage is applied to the seriesconnected circuit. Since glow starter switches 8 and 9-are normallyopen, current will be shunted aroundlamp 5 through impedance 7, and beapplied entirely to glow'switch 9, which isthen caused to glow andclose. Substantially all .of'the-current then is applied to filaments 6Aand 6B, of sufficientlyhigh voltage to cause lamp 6 to break down andignite. Thereupon, since very little resistance exists in a lit gaseousdischarge lamp, substantially all of the current will be applied to glowswitch 8, thus causing it to glow and close. This causes substantialvoltage to be applied to the filaments of lamp 5, thereby causing it toignite. Flow switch 9 in the meantime has cooled and opened. The sameoccuring later with flow switch 8 after ignition of lamp 5.

Impedance 7 is of sufficient value to enable shunting of initial currentaround lamp 5 thus causing lamp 6 to ignite after glow switch 9 hasclosed, and also to enable glow switch 8 to operate after ignition oflamp 6. Impedance 7 also prevents any excess current from harming thecircuit in the event of any element breakdown.

The filter inductor 18 is not necessary to the operation of the circuit,but may be used to obtain further current stability. Its size need notbe large.

As depicted, the transformer comprises a magnetic core having twosections. On one section is wound primary windings 2A and 28. Also woundon the same one section commonly with the primary windings 2A and 2B aresecondary windings 3A and 3C. Wound about the other section of core 1are windings (secondary) 3B and 3D. It has been discovered that theother section through flux leakage will act as a separate inductor inthe circuit. Flux leakage device 1A, enables greater flux leakage.Although the ratio of commonly wound secondary windings 3A and 3C to thetotal number of secondary windings 3A, 3B, 3C and 3D, depends upon theother circuit elements used, it has been found that when this ratio iswith in the range of from 10 to percent, the circuit would be mosteffective. Advantageously, the windings 3B and 3D, act as both secondarywinding of a transformer and also as a choke ballast. Thus, high voltagenecessary for starting the lamps is obtainable without the use of heavyduty chokes, and ballast is provided to compensate for the surge ofcurrent resulting from the ignition of the lamps without use of heavyduty chokes.

Although the circuit of HG. l is depicted as showing a pair of lamps,together with flow switches 8 and 9 connected in parallel therewith, theprinciples of this invention are applicable to one or more gaseousdischarge devices without use of such glow switches.

In FIG. 2, there is depicted a circuit which does not use flow switchesand uses another type of gaseous discharge devices, a pair of rapidstart (FLR) fluorescent lamps 5 and 6. The elements which are common toFIGS. 1 and 2 are labeled with the same numerals and letters. Sincetheir functions are similar, they will not be discussed or describedagain in connection with this figure The difference between the twofigures are the addition of additional third windings 3E, 3F, and 36 onmagnetic core 1, to which windings are, respectively, connectedfilaments 5A, interconnected filaments 5B and 6A, and filament 6B. Therapid start fluorescent lamps 5 and 6, have grounded static shield 13and 14 respectively.

The percentage of number of secondary windings 3A and 3C to the totalnumber of secondary windings 3A, 3B, 3C and 3D ranges between 10 percentand 80 percent. ln this case, when 80 watt rapid start-type (FLR-XO)fluorescent lamps were used, the percentage was about 40 percent.

The high impedance element 7 is of such value as to not short circuitlamp 5, and to prevent the full current from flowing to lamp 6, yetenable flow of small initial trickle discharge current to lamp 6 whenthe starting voltage is initially applied thereto. One example of suchan impedance is a capacitor of 0.2 microfarad capacity.

To operate this embodiment, switch S is closed. Sufficient startingvoltage is induced in secondary windings 3A, 3B, 3C, 3D. The startingvoltage will initially be applied to filament 5A, filament 6B, andfilament 6A through impedance 7. None of the lamps will igniteinstantaneously since insufficient voltage will be applied to any ofthem. However, small initial trickle discharge will occur first in lamp5 when the starting voltage is initially applied. This would lower theresistance of lamp 6. An initial trickle discharge of lamp 5 will thenoccur and cause decrease in the impedance of lamp 5, and increase thestarting voltage applied thereto. This action in turn causes startingvoltage to increase at lamp 6, thus further lowering its impedance, asthe trickle discharge increases.

This differential stepwise ignition process is repeated until the totalinternal impedance of the two lamps 5 and 6 are sufficiently low toenable the starting voltage to pass current through the two lamps.Although lamp 6 is the first to start the initial trickle discharge, thestarting of both lamps is substantially simultaneous, since they areboth connected in series and impedance element 7 is of sufficient valueto prevent initial flow of full lamp current to either.

ln one example, the following elements were used in the circuit of FIG.2: a pair of 80 watt rapid start-type fluorescent lamps (FLR-80),primary voltage of 100 volts at 50 cycles, rated starting voltage of 305volts or 152.5 volts per lamp, rated lamp current of 0.90 amps, minimumstarting voltage at the primary of 85 volts (equivalent to 260 volts or130 volts per lamp at the secondary circuit). Tests were run on thecircuit and the results are tabulated below.

The stability of lamp current was found to be satisfactory when testswere run with primary voltage varying from 70 to 120 volts. lt isunderstood that the foregoing is only illustrative of the principles ofthis invention and that numerous other changes and modification would beobvious to one skilled in the art without departing from the spirit andscope of this invention.

I claim:

1. in combination:

1. a pair of fluorescent lamps:

2. a first high impedance means connected in shunt circuit across one ofsaid pair of fluorescent lamps;

3. a second impedance means comprising a capacitor and a high resistanceconnected in shunt circuit across said capacitor; 4. a voltage source;5. a transformer comprising a. closed magnetic core having fourinterconnected branches, b. a pair of primary windings wound about afirst pair of said branches, 0. two pairs of secondary windings, one ofsaid two pairs wound about said first pair of said branches commonlywith said primary windings, and the other of said two pairs wound aboutthe other pair of said branches, said first pair having a number ofturns comprising from 10 percent to percent of the total number of turnsof said two pairs of secondary windings, and, d. flux leakage meansdisposed between said first pair and said second pair of said branches;6. means for serially connecting said primary windings to each other; 7.switch means for connecting said series connected primary winding tosaid voltage source; 8. means for serially connecting said secondarywindings to each other; 9. and means for connecting in series circuitsaid serially connected secondary windings, said serially connectedfluorescent lamps and said second impedance, whereby operation of saidswitch means causes energization of said primary windings and generationof voltage in said secondary windings thereby to place voltage acrossboth of said fluorescent lamps, with said first impedance means shuntingsubstantially all of said voltage to the other of said pair offluorescent lamps, thereby to cause ignition thereof, thereaftersubstantially of said voltage is placed across said one of said pair offluorescent lamps thereby to cause ignition thereof, said leakage meansthereupon causing lowering of voltage across both of said fluorescentlamps.

2. The combination of claim 1, wherein said fluorescent lamps comprisepreheated-type fluorescent lamps, and a flow starter switch is connectedin shunt circuit across each of said lamps.

3. The combination of claim 1, wherein said fluorescent lamps compriserapid start-type fluorescent lamps, each having heating elements, andwherein said transformer has a plurality of third winding wound on saidmagnetic core, and means for connecting said third windings to saidheating elements.

1. In combination:
 1. a pair of fluorescent lamps:
 2. a first highimpedance means connected in shunt circuit across one of said pair offluorescent lamps;
 3. a second impedance means comprising a capacitorand a high resistance connected in shunt circuit across said capacitor;4. a voltage source;
 5. a transformer comprising a. closed magnetic corehaving four interconnected branches, b. a pair of primary windings woundabout a first pair of said branches, c. two pairs of secondary windings,one of said two pairs wound about said first pair of said branchescommonly with said primary windings, and the other of said two pairswound about the other pair of said branches, said first pair having anumber of turns comprising from 10 percent to 80 percent of the totalnumber of turns of said two pairs of secondary windings, and, d. fluxleakage means disposed between said first pair anD said second pair ofsaid branches;
 6. means for serially connecting said primary windings toeach other;
 7. switch means for connecting said series connected primarywinding to said voltage source;
 8. means for serially connecting saidsecondary windings to each other;
 9. and means for connecting in seriescircuit said serially connected secondary windings, said seriallyconnected fluorescent lamps and said second impedance, whereby operationof said switch means causes energization of said primary windings andgeneration of voltage in said secondary windings thereby to placevoltage across both of said fluorescent lamps, with said first impedancemeans shunting substantially all of said voltage to the other of saidpair of fluorescent lamps, thereby to cause ignition thereof, thereaftersubstantially of said voltage is placed across said one of said pair offluorescent lamps thereby to cause ignition thereof, said leakage meansthereupon causing lowering of voltage across both of said fluorescentlamps.
 2. a first high impedance means connected in shunt circuit acrossone of said pair of fluorescent lamps;
 2. The combination of claim 1,wherein said fluorescent lamps comprise preheated-type fluorescentlamps, and a flow starter switch is connected in shunt circuit acrosseach of said lamps.
 3. The combination of claim 1, wherein saidfluorescent lamps comprise rapid start-type fluorescent lamps, eachhaving heating elements, and wherein said transformer has a plurality ofthird winding wound on said magnetic core, and means for connecting saidthird windings to said heating elements.
 3. a second impedance meanscomprising a capacitor and a high resistance connected in shunt circuitacross said capacitor;
 4. a voltage source;
 5. a transformer comprisinga. closed magnetic core having four interconnected branches, b. a pairof primary windings wound about a first pair of said branches, c. twopairs of secondary windings, one of said two pairs wound about saidfirst pair of said branches commonly with said primary windings, and theother of said two pairs wound about the other pair of said branches,said first pair having a number of turns comprising from 10 percent to80 percent of the total number of turns of said two pairs of secondarywindings, and, d. flux leakage means disposed between said first pairanD said second pair of said branches;
 6. means for serially connectingsaid primary windings to each other;
 7. switch means for connecting saidseries connected primary winding to said voltage source;
 8. means forserially connecting said secondary windings to each other;
 9. and meansfor connecting in series circuit said serially connected secondarywindings, said serially connected fluorescent lamps and said secondimpedance, whereby operation of said switch means causes energization ofsaid primary windings and generation of voltage in said secondarywindings thereby to place voltage across both of said fluorescent lamps,with said first impedance means shunting substantially all of saidvoltage to the other of said pair of fluorescent lamps, thereby to causeignition thereof, thereafter substantially of said voltage is placedacross said one of said pair of fluorescent lamps thereby to causeignition thereof, said leakage means thereupon causing lowering ofvoltage across both of said fluorescent lamps.